#r "nuget:Utf8Json"

using Utf8Json; 
using System.Runtime.Serialization;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Item 
{
    
    public string Name {get;set;}
    public int Value {get;set;}
    public double Weight {get;set;}
    [IgnoreDataMember]
    public ItemCollection Parent {get;set;}
}

public class ItemCollection : KeyedCollection<string, Item>
{
    protected override string GetKeyForItem(Item item) { return item.Name; }
}

var first = new Item() {Name = "ddd", Value = 5, Weight = 54.2}; 

Console.WriteLine( JsonSerializer.ToJsonString(first)); 

var Col = new ItemCollection(); 
Col.Add(first);

Console.WriteLine( JsonSerializer.ToJsonString(Col));

var ColDes =  JsonSerializer.Deserialize<ItemCollection>(JsonSerializer.ToJsonString(Col));